Interlocking electrical plug assembly



Nov. 20, 1956 B. F. NAUSLAR INTERLOCKING ELECTRICAL PLUG ASSEMBLY FiledMay 15, 1953 INVENTOR. BENJAMIN F. NAUSLAR mamm AGENT$ FOR APPLICANTINTERLOCKING ELECTRHiAL PLUG ASSEMBLY Benjamin F. Nauslar, San Diego,Calif.

Application May 15, 1953, Serial No. 355,299

1 Claim. (Cl. 339--168) This application is a continuation-in-part of mycopending application Serial No. 85,075, filed April 2, 1949, now PatentNo. 2,643,364 and relates particularly to an interlocking electricalplug assembly.

The primary object of this invention is to provide an interlockingelectrical plug assembly, the male and fe' male portions of which areinterchangeably useable with conventional plug of the same size.

Another object of this invention is to provide an electrical plugassembly in which the electrical contacts are integral with the pluglocking means, thus simplifying and decreasing the cost of constructionof these elements.

Another object of this invention is to provide an interlockingelectrical plug assembly, the structure of which may be applied toconventional plugs with the. minimum of modification.

Another object of this invention is to provide an interlockingelectrical plug assembly which is adapted for fabrication from manydifferent materials, so that the choice of material can be according tothe dictates of availability and price considerations, the exact sizesand proportions being matters easily determined to suit particularconditions and needs.

Another object of this invention is to provide an interlockingelectrical plug assembly which is inexpensive and practicable tomanufacture.

Finally, it is an object to provide an interlocking electrical plugassembly of the aforementioned character which is simple, safe andconvenient to operate, and which will give generally efficient anddurable service.

With these and other objects definitely in view, this invention consistsin the novel construction, combination and arrangement of elements andportions, as will be hereinafter fully described in the specification,particularly pointed out in the claim, and illustrated in the drawingwhich forms a material part of this disclosure and wherein similarcharacters of reference indicate similar or identical elements andportions throughout the specification and throughout the views of thedrawing, and in which:

Fig. l is a perspective view, partially cut away, of the interlockedmale and female plug portions.

Fig. 2 is a side elevation view of the female plug portion.

Fig. 3 is a sectional view taken on the line 33 of Fig. 2.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 3.

Fig. 5 is a perspective view of the male plug portion.

Fig. 6 is a fragmentary sectional view of a wall type electrical outletshowing the female plug portion as adapted for use in a wall typeoutlet.

Fig. 7 is a perspective view of the male plug portion used with the walltype outlet of Fig. 6.

Referring now to the drawing, the device comprises, briefly, a male plugportion 10 having a pair of contact prongs 12 and 14, and a female plugportion 16 having therein a pair of resilient contacts 18 and 20.

nited States atent 2 a The male plug 10 comprises a frame 21 ofconventional construction, but the prongs 12 and 14 are provided attheir free ends with projections or lips 22 and 24 respectively, the lip22 being vertically opposed to the lip 24 as shown in Fig. 5. The prongs12 and14 are, of course,

electrically connected to a two-wire conductor cable 26..

The female plug 16 comprises a frame 28 of substantially conventionalconstruction having a pair of slotted. openings 3i) through which theprongs of the maleplug are inserted. Within the frame 28 and formedintegrally therewith are a pair of ledges 32 disposed laterally of.

the slotted openings 30. r

The contacts 18 and 20 are inserted in the arcuate cavities 34 betweenthe ledges 32 and the inner wall of the frame 28, being retained thereinand substantially supported by means of insulation plates 36 and. 38respectively.

The contact 18 is positioned toward. one side of the of substantiallyconventional design, wlhich enablesvtheplug to be screwed into astandard electrical socket. The

contact 20 is folded over the end of the insulation plate.

3%, as indicated at 48, and is in electricalcontact with the screwed cap46 when the female plug is assembled. r

The contact 18 is extended outwardly throughthe end of the screwed cap46 and through the insulating disc 50.

attached thereto, a suitable aperture being. provided in the screwed capto prevent an electrical connection with said contact. The protrudingend of the contact18 is bent as indicated at 52 to rest on theinsulating disc 50, and isfastened by means of a screw 54 whichisscrewed into the central pillar 42. This screw 54 holds the insulatingdisc 50 and the cap 4-6 to the'framejand conr pletes the assembly of thefemale plug. 1 i

It will be seen that when the male plug 10 is inserted into the femaleplug 16, the prongs 12 and 14 will strike the contacts 18 and 20. As theprongs are advanced into the female plug, the lips 22 and 24 on saidprongs will pass the ends of the ledges 32. At this point, the opposedresilient loops 4t) and 44 pressing against the opposite sides of saidprongs will bias the male plug to rotate a few degrees relative to thefemale plug, about an axis common to both plugs, so that the lips 22 and24 will be forced over the ledges 32. In this position, the male plugcannot be removed by a direct axial pull, but must be rotated slightlyagainst the pressure of the resilient loops 49 and 44, in order todisengage the lips 22 and 24 from the ledges 32.

The loops 4i) and 44 also being the electrical contacts of the femaleplug 16, a good electrical connection is made with the male plug 10while the prongs are locked in position.

It should be noted that the male plug 10 as shown in Fig. 1 has the lips22 and 24 disposed so that the plug must be rotated in a clockwisedirection in order to unlock the prongs. This clockwise rotation ensuresthat the female plug 16 will not be unscrewed from its socket duringremoval :of the male plug, most such femal plugs having conventionalclockwise threads.

A slightly modified form of the invention is shown in Fig. 6 in whichthe structure is applied to a wall type electrical outlet. These outletsnormally comprise a pair of female plugs, one of which has beenillustrated. The female plug 56 comprises a frame 58 having a pair ofslotted openings 60 through which the prongs of the male plug areinserted. The frame 58 is fastened to a mounting plate 62 which isattached to a conventional outlet box 64.

Within the frame 58 are a pair of ledges 66 similar in character andarrangement to the ledges 32 previously described. The contacts 68 arelocated behind the ledges 66 and are provided with terminals 70protruding through the frame 58, to enable the electrical connections tobe made. The contacts 68 have resilient loops 72 and are arranged inopposed positions in alignment with the slotted openings 60 in a mannersimilar to that previously described.

The male plug 74 comprises a frame 17 in which are fitted a pair ofprongs 76 and 78, electrically connected to a two-wire conductor cable26. The prongs 76 and 78 are provided at their free ends withprojections or lips 80 and 82 respectively, the lip 80 being opposed tothe lip 82, or extending in the opposite direction, as shown in Fig. 7.It should be noted that the prongs 76 and 78 are arranged so thatcounter-clockwise rotation is necessary in order to remove the male plug74 from the female plug 56, this being the opposite to the rotationrequired to unlock the female plug 16. This counter-clockwise rotationis more suited for use with wall type outlets wherein no provisionagainst unscrewing is required, in contradistiction to the case of thescrewed type female plug shown in Figs. 1 to 4. The counter-clockwiserotation is consistent with the natural tendency when unscrewing orremoving a plug or similar article and is therefore preferable when noprovision against loosening is required.

The instant invention offers distinct advantages over conventional plugsby preventing accidental removal of the male plug due to a pull on theconductor 26. As an example, when. using an electric iron, theelectrical cord is often extended to its full length, with the resultthat the male plug may be disconnected. The plug described hereinprevents such an occurrence by locking the male plug firmly in placeuntil removed intentionally.

The operation of this invention will be clearly comprehended from aconsideration of the foregoing description of the mechanical detailsthereof, taken in connection with the drawing and the above recitedobjects.

It will be obvious that all said objects are amply achieved by thisinvention.

Further description would appear to be unnecessary.

It is understood that minor variation from the form of the inventiondisclosed herein may be made without departure from the spirit and scopeof the invention, and that the specification and drawing are to beconsidered as merely illustrative rather than limiting.

I claim:

An interlocking electrical plug assembly including a female plug and amale plug having a common axis, said female plug comprising a framehaving a central pillar, a pair of slotted openings in said frame spacedon opposite sides of said pillar, ledges within said frame disposedlaterally of said openings and defining arcuate cavities with the wallsof said frame, a pair of looped spring contacts disposed on oppositesides of said pillar and positioned in said cavities, the loops thereofbeing opposed to each other and aligned with said openings, insulatedplates supporting said spring contacts and holding them in saidcavities, a screwed electrically conductive cap secured to said frameand having a central. terminal insulated from the cap, one of saidspring contacts being connected to said cap and the other of said springcontacts being connected to said terminal, said male plug comprising aframe having a pair of prongs spaced to align with said openings, saidprongs each having a projecting lip, said lips being on opposite sidesof said prongs, said spring contacts engaging said prongs on oppositesides thereof and urging said prongs together with said male plug frameto rotate slightly in one direction about said axis relative to saidfemale plug and said lips engaging said ledges when said male plug isrotated slightly in said direction after insertion into the female plug.

References Cited in the file of this patent UNITED STATES PATENTS1,376,068 Benjamin Apr. 26, 1921 1,753,064 Nonneman Apr. 1, 19302,026,755 Stem Jan. 7, 1936 2,149,550 Richards et a1. Mar. 7, 19392,220,810 Bright Nov. 5, 1940 2,643,364 Nauslar June 23, 1953

